The present invention relates to a numerical controlling method, as well as to a numerical controlling system, and, more particularly, to a numerical controlling method and system which permit a reduction of the number of cables between the numerical control apparatus and the machine to be controlled.
In a numerical controlling system having a numerical controlling apparatus and a machine to be controlled such as machine tool, robot or the like, the desired control of machining or robot tasks is performed through the exchange of signals between the numerical control apparatus and the machine. For instance, various commands such as miscellaneous function commands (M function commands), tool exchange commands (T function commands), spindle rotation speed commands (S function commands) and so forth are derived from a punched paper tape or the like. When such a command is issued, the numerical control apparatus delivers the command to the machine side so that the machine actuates machine elements such as relays in accordance with the delivered command. When the operation is completed in compliance with the command, the machine produces and sends an operation completion signal FIN back to the numerical control apparatus. Various limit switches, such as over-travel detection switches, as well as sensors, are provided on the machine side. The states of these limit switches and sensors are transmitted to the numerical control apparatus to enable the latter to perform the necessary processing operations.
In the conventional numerical controlling system, the numerical control apparatus and the machine are connected by a numerous data transmitting cables, resulting in complicated wiring and high expense. This problem is particularly serious when the machine is located at a distance from the numerical control apparatus.